Parking lights, side markers, daytime running lights, and tail lights show the vehicle's presence, position, size, and direction of travel. Reflectors make a vehicle with switched off or failed lights safely visible after dark. This is in contrast to the vehicle's forward illumination lights which light the driver's way forward at night or make driving safer during the day.
Multifunction combination lights may contain a mix of forward illumination lights, signal lights, and reflectors. Validating a vehicle's lights means checking that all required ones are present, that all are in good condition, and that all function correctly. Basically, all lights and reflectors installed on the vehicle must function, even optional ones.
Current methods for validating external vehicle lighting include limited internal circuit diagnostics and/or manual inspection when the vehicle is not being driven. Hence, there is a desire to have a method of automatically detecting the degradation or failure of external vehicle lights before, during or after vehicle operation independently from existing internal circuit diagnostics.